The invention relates to a device for the reduction of bending vibrations on a rigid supporting pipe disposed longitudinally in a vehicle, said pipe being connected with a drive unit at the rear, and with an engine at the front, said engine being in driving connection with the rear drive unit via a drive shaft disposed inside the said supporting pipe.
A device is known [German Auslegeschrift 25 08 212, which corresponds to U.S. Pat. No. 4,077,233] for damping torsional and bending vibrations in the drive system of automobiles which makes use of a vibration suppressor. The vibration suppressor is connected with the driving part of the drive system.
In a vehicle design with an engine disposed in the front of the vehicle and a drive unit at the rear, the engine is connected with the drive unit by means of a rigid supporting pipe, said drive unit being in driving connection with the engine via a drive shaft disposed in the supporting pipe. Such an assembly, also called a transaxle assembly, is subject to vibrations in general, and to bending vibrations in particular, from the free inertial forces of the engine, and particularly, in 4-cylinder engines where inertial forces of the second order, which are in proportion to the rpm of the engine occur and whereby comfort is diminished because of increased noise inside the vehicle, and vibrations.
The invention is intended to develop a device of the mentioned type with which comfort is enhanced by a lowering of the internal noise level and a reduction of vibration by decomposition of the bending vibrations on the transaxle assembly.
The problem is solved according to a preferred embodiment of the invention by a vibration suppressor connected with the supporting pipe, the suppressing mass of the device being fastened to the supporting pipe without contact with the drive shaft, by elastic means, whereby, according to the preferred embodiment of the invention, it is provided that the vibration suppressor is disposed within the supporting pipe in a zone of high vibration (the vibration antinode), and the suppressing mass is braced in the supporting pipe by means of elastic rings. The elastic rings are made of an elastic material, especially elastomer, or a technically equivalent material.
According to another aspect of the invention, it is provided that the suppressing mass has the configuration of a sleeve and presents receivers at its ends, for the elastic rings.
According to yet another feature of the invention, the suppressing mass of the vibration suppressor is arcuate, bears on an elastic element fixed in the supporting pipe, and is disposed without contact between the supporting pipe and the drive shaft.
According to another preferred embodiment of the invention, a vibration damping device is disposed outside of the supporting pipe and the suppressing mass is connected therewith by an elastic element. The elastic element in this case is vulcanized onto supporting plates that are connected on one side with the supporting pipe and on the other with the suppressing mass, via fastening means. In a special arrangement of the vibration suppressor on the vehicle, the damping device is disposed between the supporting pipe and an upstream muffler for an exhaust line, the device being arcuate in configuration and partly surrounding the said upstream muffler, at a distance.
Among the advantages that the invention offers is the fact that passenger comfort is increased by reduction of the vibrations on the assembly. This reduction is made possible by a decomposition of bending vibrations on the supporting pipe that are typical of the assembly by means of the vibration suppressor. The suppressor is disposed inside or outside the supporting pipe, in a simple construction. The vibration may also be made as a part which can be installed subsequently on the supporting pipe. By use of strongly damping elastomers and special volume selection of the elastomer, there can also be a general reduction of vibration on the supporting pipe, by dynamic coupling of the suppressing mass.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.